Extended battery pack

Charles Pax charles.pax at gmail.com
Thu Aug 21 05:20:17 CEST 2008

On Wed, Aug 20, 2008 at 10:31 PM, Robert William Hutton <
rwh at helms-deep.cable.nu> wrote:

> Hi All,
> In order to use TangoGPS over extended periods, I created myself an
> extended battery pack for the Neo FreeRunner from bits and pieces I had
> lying around.  Check out my blog post for instructions:
> http://helms-deep.cable.nu/~rwh/blog/?p=42<http://helms-deep.cable.nu/%7Erwh/blog/?p=42>

Pretty cool, Rob. Thanks for sharing this.

The following are three questions Rob has posted on the above website.
- Can we charge the neo at 1000mA from AA batteries without damaging
anything?  If so, would it be worth fitting the 47.5 kOhm resistor between
the "ID" and "GND" pins of the USB connector?
- What is the most efficient way to use the external batteries?  Intuitively
I suspect it's best to not charge the internal battery from the external
ones as there would be a lot of inefficiency involved.  Perhaps running at
100mA charge rate most of the time, then switching to 500mA when the neo's
battery got low?
- Does anyone know how much current the neo draws when it's set to (say)
500mA and the battery fills up?  It would be a very inefficient way to use
the external batteries and would generate a lot of heat if it continued to
draw more current than it needed.

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